What it means
NOx Sensor Circuit (Bank 1 Sensor 2): an electrical fault is present in the circuit.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The NOx sensor at bank 1, sensor 2 measures nitrogen oxides in the exhaust downstream in the emissions system and sends an electrical signal to the control module. This circuit code sets when the module detects an electrical fault in that sensor's circuit; it does not specify whether the sensor or wiring is at fault.
Common causes
Most likely first.
- Failed NOx sensor element or electronics
- Damaged or corroded sensor wiring or connector
- Open or short in the sensor circuit
- Exhaust leak near the sensor
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Scan for related emissions codes and review freeze-frame data to see the conditions when the bank 1 sensor 2 circuit fault appeared.
- Locate bank 1 sensor 2 and inspect its connector and harness for corrosion, heat damage, chafing, or loose pins.
- Check for an exhaust leak near the sensor that could affect its readings or indicate a damaged installation area.
- Use scan-tool data to see whether the sensor communicates and produces plausible readings once the system is operating.
- Test the sensor's power, ground, and signal circuits for opens, shorts, and poor connections according to the wiring diagram and manufacturer's specification.
Common fixes
- Repair damaged or corroded wiring and connector terminals.
- Repair an exhaust leak near bank 1 sensor 2.
- Replace the bank 1 sensor 2 NOx sensor if its electronics fail circuit testing.
Can I keep driving?
You can usually drive cautiously if the engine runs normally, but address the fault promptly because emissions monitoring may be disabled and a DEF warning or eventual start restriction may occur. Stop if the vehicle develops a serious drivability problem.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.